One of thirteen children?

Helen Fitzgerald has an article in the Guardian about being one of 13 children and growing up in Australia in the 70's.
From her description I don't think I would want to be one of 13 children. I most certainly would not want to be one of twenty.
I once visited a family with twenty children. Before you all panic I need to point out that a widow had married a widower and families of 9 and 11 had come together. The house was run on timetables and rosters. It had to be. I imagine that a house with 13 children would have to be run in a similar fashion if chaos was not to ensue. 
I have a distant cousin who has six children and I know other families with six and one with eight. It's simply too many. (I will also add that all these families come from "fundamentalist Christian" backgrounds and are home-schooled.)
I know there are people who will read this and say "What's wrong with having six or eight children if you can afford it?"
It's simply irresponsible in my book. The world's population cannot increase indefinitely.
My brother has two children. One of my sisters has two children. My other sister has chosen dogs over children.
Yes, I am one of four. It was an average size family when I was born. A quarter of a century after my siblings were born they decided it was responsible to do no more than replace themselves.
I know there are worries in this country, and even more in Japan, that declining birth rates mean there will not be enough young people to support the ageing population.  And yes, it will be a problem.
I am the one who cared for both my parents. I still look after the Senior Cat. It's the way things worked out. He would need to live in some sort of aged care accommodation if one of us could not care for him. He'd hate it - in fact I doubt he would be alive. At the present he is still active even if it takes him "forever" to get up and eat breakfast and water his garden and do a little light woodwork. I am aware that the time is approaching when he will not be safe on his beloved gopher and that will isolate him as he can no longer use public transport.  And yes, there are times when his post-prandial afternoon cat-nap is longer than others - and I creep in to make sure he is still breathing.
I am learning that my work can be done at other times. We prowled off out to lunch with Middle-Cat on his birthday and spent an hour in a bookshop. I had to go on working well into the evening to catch up but it didn't matter. One day I am not going to need to arrange my day like that.
Having a lot of children doesn't necessarily mean that they will be there for you in old age. My brother and one of my sisters live in other states. They are in contact each week. Middle-Cat lives not far away and is good at helping with medical appointments and occasionally taking the Senior Cat off somewhere they both want to go. But I know many other elderly and old people who simply have nobody close to hand. Their children are living interstate or even abroad or even just in another part of the state. I know someone who had seven children - and none of them live here.
I don't think having a large family is the answer - it's whether your family is there. It's being there that counts.